If they're not hard to learn, then imo it's not a "skilled trade".

> those who know it just pretend they are hard to keep people out.

> Of course with an engineering background I know how to read all the different tables and understand where the numbers came from.

If you're an EE and you're referring to electricians, I would argue that electrical work is not an easy concept for most of the population which is one reason for its market demand.